Beam delivery system for corneal surgery

ABSTRACT

An apparatus and method for delivering radiant energy beams onto an area of a cornea in a line focus to create a linear incisions. The radiant energy beams may be focused in a linear configuration onto the external surface of the cornea or onto intrastromal areas of the cornea of an eye to ablate the cornea in a radial slot, circumferential curved slot, or lenticular pattern, and thereby modify its curvature and refractive power. The apparatus includes an array of central reflectors and an assembly of peripheral reflectors. Each central reflector is associated with a respective peripheral reflector so that a beam reflected by the central reflector is intercepted by its associated peripheral reflector and is again reflected to precisely incise either external or internal areas of the cornea. Each peripheral reflector has a curved reflective surface to provide a line focus on the cornea, including both rectilinear and curvilinear line focus to create radial and circumferential curved incisions. In a modified embodiment, the assembly of peripheral reflectors and the array of central reflectors rotate to permit lathing of the cornea.

RELATED APPLICATIONS

This is a continuation-in-part application of Ser. No. 07/812,163 filedon Dec. 23, 1992, which is a continuation of Ser. No. 07/598,793 filedon Oct. 17, 1990, now U.S. Pat. No. 5,074,859, which is a continuationof Ser. No. 07/464,637 filed on Jan. 5, 1990, now abandoned, which is acontinuation of Ser. No. 07/176,765 filed on Apr. 1, 1988, nowabandoned.

FIELD OF THE INVENTION

The invention relates to an apparatus for delivering radiant energybeams onto the cornea of an eye. More specifically, the inventionrelates to an array of central reflectors for intercepting a radiantenergy beam and reflecting and splitting the beam along several paths toan assembly of peripheral reflectors radially spaced therefrom, which inturn focus and reflect the beams onto the cornea in line configurations.The central reflector array and the peripheral reflector assembly can berotated as a single unit relative to the eye for scanning operations.The invention when used in a stationary position can ablate the corneavia simultaneously applied radial or circumferential incisions, and whenrotated can re-profile the cornea via photolathing.

BACKGROUND OF THE INVENTION

The use of high intensity light sources such as lasers for cutting andreshaping eyes has expanded in recent years in part due to the superiorprecision, controllability and safety which such cutting technologyoffers over other cutting technologies, such as mechanical cutting ofthe eye. One type of ophthalmic surgical procedure for whichhigh-intensity light radiation is particularly well suited is the radialkeratotomy procedure in which a number of radial incisions are made onthe cornea of the eye to change the curvature of the cornea.

Several methods and apparatus for performing radial keratotomies withlasers have been proposed. See, for example, U.S. Pat. No. 4,648,400 toSchneider et al; and U.S. Pat. No. 4,665,913 to L'Esperance, Jr.Schneider et al describe the use of lasers to selectively ablate thecornea of the eye by directing the laser beam through a generally planarmask having radial slots. The radial slots of the mask permit portionsof the laser beam to pass through the mask and incise the cornea in apattern of circumferentially spaced radial incisions.

Lasers have also been used to ablate an annular portion of the cornea byscanning or variably attenuating the laser beam. Such scanning changesthe front surface of the cornea to a different optical curvature,thereby changing the refraction of the eye. See, for example, U.S. Pat.No. 4,669,466 to L'Esperance.

In such an application, it is desirable to deliver uniform beam energyalong the curved scanning path. However, since the cornea presents aconvexly curved surface to the laser beam, the outer circumferentialportions of the cornea lie at further distances from the beam sourcethan those portions at or near the center of the cornea. Thus, the laserbeam incidents the cornea with a different angle along the cornea'sconstantly changing surface which causes variation of the energy densityof the laser beam in a direction perpendicular to the corneal surface.

Using a mask to produce corneal incisions does not focus the beam on thecorneal surface but merely projects the beam toward the surface.

Additionally, the energy of the laser beam may not be distributeduniformly due to the position of the mask relative to the beam. Anon-uniform distribution of energy results in differing depths of theradial incisions, leading to an improper restructuring of the curvatureof the cornea.

More recently, laser systems have been developed to ablate intrastromalareas of a cornea without ablating or piecing the external surface ofthe cornea. These laser systems focus the lower beams as a spot oneither external or intrastromal areas of the cornea to be ablated. Thus,to create a linear incision, the laser must ablate a plurality of spotsalong the line of incisions. An example of a laser system employing spotfocus ablation is disclosed in U.S. Pat. No. 4,907,586 to Bille et al,which is hereby incorporated herein by reference.

SUMMARY OF THE INVENTION

Accordingly, a primary object of the present invention is to provide anapparatus and method for delivering radiant energy from a radiant energysource in a line focus onto an area of the cornea to create linearincisions, including rectilinear and curvilinear incisions.

A further object of the invention is to provide an apparatus and methodwhich can simultaneously direct a number of radiant energy beams onto aneye from a single source.

A further object of the invention is to provide an apparatus and methodwhich can direct radiant energy onto an eye so as to lathe the eye andfor a lenticular ablation.

An additional object of the invention is to provide an apparatus andmethod for delivering radiant energy onto an eye which minimizes theenergy needed to incise the cornea to a desired depth via focusing ofthe radiant energy.

Another object of the invention is to provide an apparatus and methodfor controlling radiant energy to produce optical changes in an eye andmaintain substantially constant incision depth across the incision

Another object of the invention is to provide an apparatus and method ofconducting corneal surgery via focusing laser light and thus concentratethe laser energy 100 to 10,000 times to permit use of low cost laserssuch as a frequency modified YAG laser.

The foregoing objects are basically attained by providing an apparatusfor delivering radiant energy beams onto the cornea of an eye centeredon a main optical axis, the combination comprising a source of a radiantenergy beam aimed along the main optical axis; a support; an array ofdiscrete central reflectors arranged about the main optical axis forintercepting the radiant energy beam incident thereon, splitting thebeam into a plurality of beam portions, and reflecting each beam portionoutwardly of the main optical axis; a first member coupled to thesupport and the array of central reflectors for coupling the centralreflectors to the support; an assembly of discrete peripheral reflectorsoutwardly spaced from the central reflectors, each peripheral reflectorintercepts one of the reflected beam portions from an associated centralreflector and directs the intercepted beam portion generally along themain optical axis and incident onto the cornea; and a second membercoupled to the support and the peripheral reflectors for coupling theperipheral reflectors to the support, each of the peripheral reflectorsincluding a mechanism for focusing the intercepted beam portion onto anarea on the cornea separate and discrete from the incidence of the otherof the intercepted beam portions on the cornea and in a linearconfiguration.

The foregoing objects are also attained by providing a method ofablating a cornea via a radiant energy beam comprising the steps ofaligning a source of a radiant energy beam and the cornea along a mainoptical axis, emitting the radiant energy beam from the source,splitting the beam into a plurality of beam portions and reflectingthose beam portions outwardly of the main optical axis, and reflectingthe outwardly directed beam portions to produce output beam portionsincident on the cornea.

Other objects, advantages and salient features of the invention willbecome apparent from the following detailed description, which, taken inconjunction with the annexed drawings, discloses preferred embodimentsof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings which form a part of this originaldisclosure,

FIG. 1 is a front plan view of the beam delivering apparatus of thepresent invention, showing an array of central reflectors, each havingan associated peripheral reflector radially and axially spaced from it;

FIG. 2 is a cross-sectional side view of the beam directing apparatus ofFIG. 1, taken along line 2--2 in FIG. 1 and showing the apparatusaligned between a laser beam source and the cornea of an eye;

FIG. 3 is a cross-sectional side view of a modification of the apparatusof FIG. 1, having a gas conduit system for delivering gas to the ablatedsurface of the eye, a cornea alignment receptacle for positioning thecornea and a detection system for detecting the beam power densitydistribution as well as a motive assembly to rotate the reflectors;

FIG. 4 is a cross-sectional side view of another modification of theapparatus of FIG. 1, showing a second gas conduit delivery system fordelivering gas to the cornea of the eye during rotation of thereflectors;

FIG. 5 is a perspective view of a modified peripheral reflector for usein the apparatus of FIG. 1, showing the change in the radius ofcurvature of the reflector along its central axis A;

FIG. 6 is a schematic view of a cornea having radial incisions producedby a laser bee source in conjunction with the apparatus of FIGS. 1-3;

FIG. 7 is a schematic representation of a cornea having a lenticularablation after scanning the radiant energy bees directed onto the corneaby the apparatus of FIG. 4;

FIG. 8 is a schematic view of a cornea having intrastromal radialincisions produced by a laser beam source in conjunction with theapparatus of FIGS. 1-3;

FIG. 9 is a cross-sectional side view of another modification of theapparatus of FIG. 1, having modified peripheral reflectors for ablatingcircumferentially curved lines either on the external surface of thecornea, or on intrastromal areas of the cornea without disturbing,coagulating or ablating the tissue between the peripheral reflectors andthe intrastromal areas to be ablated;

FIG. 10 is a schematic view of a cornea having circumferentially curvedincisions on the external surface of the cornea;

FIG. 11 is a schematic view of a cornea having circumferentially curvedincisions on intrastromal areas of the cornea; and

FIG. 12 is a schematic view of a cornea having wedge-shaped ablations onthe external surface of the cornea formed by focusing and pivotingradial lines of radiant energy onto external areas of the cornea.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As seen in FIG. 1, a beam delivering apparatus 10 for focusing beams ofradiant energy in a linear configuration is illustrated in accordancewith a first embodiment of the present invention, and basically includesan annular array of central reflectors 12a-h and an annular assembly ofperipheral reflectors 14a-h. Peripheral reflectors 14a-h are rigidlycoupled to a rim 16. As seen in FIG. 2, rim 16 is rigidly coupled to ahub 18 by radial spokes 19, axial rods 20 and a ring 21. Centralreflectors 12a-h are coupled to hub 18.

Beam delivering apparatus 10 is rotatably supported within a support orframe 22 about a main optical axis 24 which passes through the center ofa cornea 26 of an eye. A laser beam source 30, such as a frequencymodified YAG laser for ablating external surface areas of the cornea ora frequency-doubled YAG laser for ablating intrastromal areas of thecornea, is positioned to emit a beam along axis 24 and against centralreflectors 12a-h. These reflectors split and reflect the beam ontoperipheral reflectors 14a-h which then focus and reflect the split beamsonto cornea 26.

Beams delivering apparatus 10 can be modified in a number of ways toadapt it for use in particular types of ophthalmic surgery. For example,beam delivering apparatus 10 can be modified to perform radialkeratotomy operations on the external surface of cornea 26 or onintrastromal areas of cornea 26.

Referring now more specifically to the construction and orientation ofcentral reflectors 12a-h and peripheral reflectors 14a-h for the radialkeratotomy operation, a number of equal sized central reflectors 12a-hare provided and, preferably, the number of central reflectors is aneven number more than two and less than 16, such as eight. As shogun inFIG. 1, eight equally sized central reflectors 12a-h are rigidly coupledto one another along their sides in a octagonal array. As seen in FIG.2, each central reflector 12a-h is oriented to present a slanted,outwardly facing flat surface to the beam emanating from beam source 30.The angle of each surface is about 50°-60° to axis 24.

Each peripheral reflector 14a-h is associated with one of centralreflectors 12a-h and is oriented so that its reflective surface 15,which is curved and preferably semi-cylindrical about central axis A asseen in FIG. 2 and angled at about 40°-50° to axis 24, intercepts thebeam reflected radially, outwardly by its associated central reflector.Axis A intersects main optical axis 24 at an acute angle of about40°-50°. Additionally, each peripheral reflector is oriented so as toreflect the intercept beam axially and radially inward and to focus thebeam into line focus either onto the external surface of cornea 26 oronto an intrastromal area of the cornea. The reflective surfaces of thecentral and peripheral reflectors can be mirrors or other reflectivematerial. For example, the peripheral reflectors can be replaced withholographic elements.

As schematically shown in FIG. 6, a number of radial incisions 17 arecut via photoablation in the external surface of cornea 26 during theradial keratotomy operation. Alternatively, a number of radial,intrastromal incisions 17a can be cut via photoablation in intrastromalareas of cornea 26 during a radial keratotomy operation, asschematically illustrated in FIG. 8.

Beam delivering apparatus 10 can be used to produce the external orintrastromal incisions simultaneously. As seen in FIG. 1, each centralreflector 12a-h intercepts the beam and reflects the beam towards itsassociated peripheral reflector. Central reflectors 12a-h are preferablyrotatably coupled to hub 18 via an axle 53 fitting into the hub 18 and ascrew adjustment assembly including three set screws 56 to lock thereflectors relative to hub 18. Central reflectors 12a-h can be moved asa single unit relative to hub 18 and the adjustment screws 56 can thenbe operated to adjust and fix the relative position of the centralreflectors relative to the peripheral reflectors.

The combination of central and peripheral reflectors including the rim16, hub 18, spokes 19, rods 20 and ring 21 are supported for rotationrelative to frame 22 via ball bearing assembly 38, which is coupled tothe frame and to rim 16. Thus, the angular position of the reflectorsrelative to the cornea and axis 24 can be varied. This allows angularplacement as desired of either external incisions 17 on the cornea orintrastromal incisions 17a in the cornea.

The operation of beam delivering apparatus 10 during a simple radialkeratotomy operation is as follows. Cornea 26 is immobilized byappropriate means and laser beam source 30 is positioned to emit a beamalong main optical axis 24, which passes through the center of cornea26. Beam directing apparatus 10 is positioned between beam source 30 andcornea 26 and is appropriately spaced from cornea 26 so that the beamsreflected by the central and peripheral reflectors ablate cornea 26 in apattern comprising separate and discrete areas of ablation shown in FIG.6 or FIG. 8. Once beam directing apparatus 10 is positioned, a test beamcan be emitted to test the alignment of the beams on cornea 26. Beamsource 30 is then operated to emit a radiant energy beam, such as alaser beam, which travels along axis 24, encounters the centralreflectors 12a-h, is split and radially reflected against peripheralreflectors 14a-h and is then again radially reflected and focused eitheronto the external surface of cornea 26 to simultaneously make externalincisions 17 or onto intrastromal areas of cornea 26 to simultaneouslymake intrastromal incisions 17a.

Embodiment of FIG. 3

With reference especially to FIG. 3, beam delivering system 10 can haveadded to it an eye positioning device 32, coaxial with main optical axis24 and coupled to hub 18. Eye positioning apparatus 32 has a concavesurface 34, preferably having a radius of curvature the same as theaverage radius of curvature of a cornea, so that cornea 26 can bepressed against concave surface 34 and steadied in a fixed positionduring the eye operation. Eye positioning apparatus 32 is coupled via aconnecting stem 36 to hub 18.

Eye positioning device 32 is preferably constructed of material which istransparent to the beam emitted by beam source 30 and permits completethrough transmission of the beams reflected from the central andperipheral reflectors towards cornea 26.

Beam delivering apparatus 10 and eye positioning apparatus 32 can beprovided with a gas or fluid conduit system 40 for delivering selectedgases to the cornea 26 during ablation. Gas conduit system 40 includes agas supply means 42 to supply gas along a tube 43 and a conduit 44mounted within one of the spokes 19. Conduit 44 communicates with anaxial conduit 46 within eye positioning apparatus 32 and axial conduit46 communicates with a substantially semihemispheric recess 48 definedby concave surface 34. Recess 48 communicates with conduit 46 and cornea26 and has outlets 50 for exhausting gases which have contacted cornea26.

An inert gas such as argon can be supplied by gas conduit system 40 tocontact cornea 26 and remove debris and other by-products of thesurgical operation. Additionally, a gas or liquid having a coldtemperature, such as, e.g., nitrous oxide, can be supplied by gasconduit system 40 to bathe cornea 26 in a cool environment and therebylower the metabolic state of the cornea. Lowering the metabolic state ofcornea 26 enhances the ability of the cornea to withstand traumaticinsults from the beam.

To monitor the length and intensity of the beams directed onto theexternal surface of cornea 26 or onto the intrastromal areas of cornea26 by apparatus 10, a plurality of linear detector arrays 58 can beinstalled. As seen in FIG. 3, apparatus 32 includes frustoconicalsurface 60 adapted to partially reflect a small portion (about 5%) ofthe beams directed towards cornea 26 by peripheral reflectors. Surface60 further reflects these small portions of the beams against lineardetectors 58 which are coupled to a detector means 59 for determiningthe beam intensity distribution and length. Preferably, three detectors58 are used, which are rigidly coupled to ring 21.

As seen in FIG. 3, the peripheral reflectors 14a'-h' are modified fromthose shown in FIGS. 1 and 2 by having a curved reflective surface 15'curved about an axis B which is perpendicular to axis A. This curvatureabout axis B approximates the curvature of the external surface of thecornea being ablated and provides a more even ablation and beamintensity incident on the cornea. The radius of curvature of thereflective surface 15' about axis B reduces in the radially inwarddirection so the reflected line focus is substantially coincident orparallel to with the outer surface of the cornea. Reflective surface 15'is also curved and preferably semi-cylindrical about axis A.

Beam delivering apparatus 10 of FIG. 3 therefore permits more precisionin the radial keratotomy procedure than existing systems which interposea mask between the beam source and the cornea. Unlike the beams producedby the existing systems, each portion of the beam reaching cornea 26 issubstantially uniformly focused on or in the cornea in a curved linefocus. Thus, the distribution of energy along the incision issubstantially uniform and can therefore be more precisely controlled.

Embodiment of FIG. 4

With reference now to the use of beam delivering apparatus 10 in an eyelathing, or scanning, operation as shown in FIG. 4, apparatus 10 can beespecially adapted for scanning an eye. In the embodiment shown in FIG.4, gas conduit system 40' is constructed with its conduits 44' remotefrom spokes 20, in contrast to the embodiment shown in FIG. 3 in whichconduit 44 is formed within one of the spokes 19. Ball bearing assembly64 is provided at the connection of connecting stem 36' and hub 18 sothat the central and peripheral reflectors can rotate relative to eyepositioning device 32'.

Additionally, a drive assembly 66 having a drive motor 68 for rotating agear 70 is provided. Gear 70 meshes with a ring gear 72 which is rigidlyconnected to the sides of the peripheral reflectors. Drive motor 68 ispreferably a reversible, stepping motor which allows for incrementalrotation of central reflectors 12a-h together with peripheral reflectors14a-h. Accordingly, the radial lines focused on either the external orinternal areas of the cornea can be rotated 360° or pivoted a fewdegrees in either direction for removing selected portions of thecornea. For example, a pair of radial lines can be focused onto thecornea and pivoted approximately eight degrees from both sides of the Xaxis to ablate a pair of wedge-shaped incisions 17" as seen in FIG. 12.Of course, cornea 26 can be ablated to remove areas of the cornea havinga variety of configurations depending upon various factors such as thenumber and position of lines, and the amount of rotation.

To obtain the scanning pattern schematically shown in FIG. 7 as a fulllenticular ablation, drive motor 68 is operated to rotate gear 70 which,in turn, rotates ring 72 to rotate reflectors 12a-h and 14a-h about axis24. Preferably, the reflectors are rotated at a rate of approximately200 revolutions per minute. However, rotation speed is preferablyselected for the given beam focusing width on the cornea to removematerial continuously over the cornea. Conduits 44' can be formed fromplates or tubes which are transparent to the radiant energy beam so theydo not interfere with the beach. The scanning incision 17' is shown inFIG. 7 and is in the form of a lenticular ablation in the shape of apositive, negative or toxic lens. This ablation includes the fullsurface of the cornea, although a central part can be omitted, therebyproviding an annular ablation. As used herein, "lenticular ablation"means removing corneal material via laser photoablation in the shape ofan optical lens.

Embodiment of FIG. 5

To more precisely tailor the curved line focus of the beams reflectedfrom the peripheral reflectors so that corneas of differing radii ofcurvature can be accommodated, each peripheral reflector can be designedwith a curved reflective surface whose curvature varies along the lengthof the reflector along central axis A. As shown in FIG. 5, peripheralreflector 14" has a concave surface 71 varying from a smaller radius SRto a larger radius LR. Accordingly, the beams reflected onto theexternal surface or onto the intrastromal areas of the cornea 26 fromreflectors 14" produce radial incisions of desired curved line focus andthus intensity therealong. Reflectors 14" accomplish similar result asreflectors 14a'-h' as seen in FIG. 3 but via a different reflectorconfiguration.

As shown in FIG. 1, the central reflectors can also be provided withfour inner and four outer alignment detectors 73 and 74 which monitorthe alignment of the reflectors with respect to the beam incidentthereon to allow adjustment of the laser beam to the optical centerthereof.

The beam delivering apparatus 10 of the present invention controls andfocuses the beam on the corneal surface or on intrastromal areas. Thisis beneficial since the greater the amount of energy radiated onto thecornea, the greater the risk that the cornea will be damaged byoverheating or, in the case of ultraviolet radiation, by overshock.

The overall delivery system is quite compact and can be enclosed betweenthe laser 30 and gas conduit system 40' shown in FIG. 4. This allowsfilling of the whole beam delivering system with a neutral gas tominimize ozone build-up by ultraviolet radiation.

As seen by comparing FIGS. 2 and 4, the arrangement of the central andperipheral reflectors is the same for radial keratotomy and lathing viascanning. The only difference in these procedures is the rotation of thecentral and peripheral reflectors during scanning.

Embodiment of FIG. 9

Referring now to the beam delivering apparatus 110 as shown in FIG. 9,apparatus 110 is substantially identical to the beach deliveringapparatus 10 of FIG. 3, except that peripheral reflectors 14a'-h' havebeen replaced with peripheral reflectors 114a and 114b to simultaneouslyforth two circumferentially curved incisions on areas of a cornea. Thecircumferentially curved incisions can be formed either on the externalsurface of a cornea or on intrastromal areas of a cornea.

Specifically, beam delivering apparatus 110 as seen in FIG. 9 includes apair of central reflectors 112a and 112b and an annular assembly ofperipheral reflectors 114a and 114b. Peripheral reflectors 114a and 114bare rigidly coupled to a rim 116. Rim 116 is rigidly coupled to a hub118 by radial spokes 119, axial rods 120 and a ring 121. Centralreflectors 112a and 112b are coupled to hub 118.

Beam delivering apparatus 110 is rotatably supported within a support orframe 122 about a main optical axis 124 which passes through the centerof a cornea 126 of an eye. A laser beam source 130, such as a frequencymodified YAG laser for ablating external surface areas of the cornea ora frequency-doubled YAG laser for ablating intrastromal areas of thecornea, is positioned to emit a beam along axis 124 and against centralreflectors 112a and 112b. These reflectors split and reflect the beamonto peripheral reflectors 114a and 114b which then focus and reflectthe split beams onto an area of cornea 126 in a curvilinearconfiguration.

Referring now more specifically to the construction and orientation ofcentral reflectors 112a and 112b and peripheral reflectors 114a and 114bfor performing an operation to correct an astigmatism. A pair of equalsized central reflectors 112a and 112b are provided. While only twocentral reflectors are illustrated, the number of central reflectors canbe any even number more than two and less than 16.

As shown in FIG. 9, two equally sized central reflectors 112a and 112bare rigidly coupled to one another along a pair of opposite sides by apair of connecting members 113 (only one shown) to form a wedge-shapedmirror centered on axis 124. Each central reflector 112a and 112b isoriented to present a slanted, outwardly facing flat surface to the beamemanating from beam source 130. The angle of each surface is about50°-60° to axis 124.

Each peripheral reflector 114a and 114b is associated with one of thecentral reflectors 112a and 112b and is oriented so that its reflectivesurface 115 intercepts the beam reflected radially, outwardly by itsassociated central reflector. Additionally, each peripheral reflector isoriented and constructed so as to reflect the intercept beam axially andradially inward and to focus the beam into line focus either onto theexternal surface of cornea 126 or onto an intrastromal area of thecornea. The line focus of each beam onto cornea 126 is a curvilinearline which is preferably circumferentially curved about the optical axis124. Preferably, the centers of the circumferentially curved linesfocused on cornea 126 are located on optical axis 124.

The reflective surfaces of the central and peripheral reflectors can becurved mirrors or other reflective material which focuses the beam in acurvilinear configuration onto either an external or internal areas ofthe cornea. For example, the peripheral reflectors 114a and 114b asshown in FIG. 9 are holographic elements or mirrors, which focuscircumferential curved lines onto areas of the cornea. Holographicelements or mirrors 114a and 114b can be constructed with a flatreflective surface 115 having different reflective indexes alongreflective surface 115 so that a variety of shapes and orientations oflines can be focused onto either external or internal areas of thecornea, including curvilinear lines and rectilinear lines.

As schematically shown in FIG. 10, a two circumferentially curvedincisions 117 are cut via photoablation in the external surface ofcornea 126 during an operation to correct an astigmatism. Alternatively,two circumferentially curved, intrastromal incisions 117a can be cut viaphotoablation in intrastromal areas of cornea 126 during an operation tocorrect an astigmatism, as schematically illustrated in FIG. 11.

Beam delivering apparatus 110 can be used to produce the external orintrastromal incisions simultaneously. As seen in FIG. 9, each centralreflector 112a and 112b intercepts the beam and reflects the beamtowards its associated peripheral reflector 114a and 114b. Centralreflectors 112a and 112b are preferably rotatably coupled to hub 118 viaan axle 153 fitting into the hub 118 and a screw adjustment assemblyincluding three set screws 156 to lock the reflectors relative to hub118. Central reflectors 112a and 112b can be moved as a single unitrelative to hub 118 and the adjustment screws 156 can then be operatedto adjust and fix the relative position of the central reflectorsrelative to the peripheral reflectors.

The combination of central and peripheral reflectors including the rim116, hub 118, spokes 119, rods 120 and ring 121 are supported forrotation relative to frame 122 via ball bearing assembly 138, which iscoupled to the frame and to rim 116. Thus, the angular position of thereflectors relative to cornea 126 and axis 124 can be varied. Thisallows angular placement as desired of either external incisions 117 onthe cornea or intrastromal incisions 117a in the cornea.

The operation of beam delivering apparatus 110 during a simple operationto correct an astigmatism is as follows. Cornea 126 is immobilized byappropriate means and laser beam source 130 is positioned to emit a beamalong main optical axis 124, which passes through the center of cornea126. Beam directing apparatus 110 is positioned between beam source 130and cornea 126 and is appropriately spaced from cornea 126 so that thebeams reflected by the central and peripheral reflectors ablate cornea126 in a pattern comprising separate and discrete areas of ablationshown in FIG. 10 or FIG. 11. Once beam directing apparatus 110 ispositioned, a test beam can be emitted to test the alignment of thebeams on cornea 126. Beam source 130 is then operated to emit a radiantenergy beam, such as a laser beam, which travels along axis 124,encounters the central reflectors 112a and 112b, is split and radiallyreflected against peripheral reflectors 114a and 114b and is then againradially reflected and focused either onto the external surface ofcornea 126 to simultaneously make external incisions 117 or ontointrastromal areas of cornea 126 to simultaneously make intrastromalincisions 117a.

A drive assembly 166 having a drive motor 168 for rotating a gear 170 isprovided. Gear 170 meshes with a ring gear 172 which is rigidlyconnected to the sides of the peripheral reflectors. Drive motor 168 ispreferably a reversible, stepping motor which allows for incrementalrotation of central reflectors 112a and 112b together with peripheralreflectors 114a and 114b. Accordingly, the circumferentially curvedlines, which are focused on either external or internal areas of thecornea, can be rotated 360° or pivoted a few degrees to remove selectedportions of the cornea.

It should be apparent to those skilled in the art that a plurality ofcurvilinear lines can be focused onto the cornea at various positions toablate the cornea as required to correct the patient's vision.

Beam delivering apparatus 110 and eye positioning apparatus 132 can beprovided with a gas or fluid conduit system 140 for delivering selectedgases to the cornea 126 during ablation. Gas conduit system 140 includesa gas supply means 142 to supply gas along a tube 143 and a conduit 144mounted within one of the spokes 119. Conduit 144 communicates with anaxial conduit 146 within eye positioning apparatus 132 and axial conduit146 communicates with a substantially semihemispheric recess 148 definedby concave surface 134. Recess 148 communicates with conduit 146 andcornea 126 and has outlets 150 for exhausting gases which have contactedcornea 126.

An inert gas such as argon can be supplied by gas conduit system 140 tocontact cornea 126 and remove debris and other by-products of thesurgical operation. Additionally, a gas or liquid having a coldtemperature, such as, e.g., nitrous oxide, can be supplied by gasconduit system 140 to bathe cornea 126 in a cool environment and therebylower the metabolic state of the cornea. Lowering the metabolic state ofcornea 126 enhances the ability of the cornea to withstand traumaticinsults from the beam.

While various advantageous embodiments have been chosen to illustratethe invention, it will be understood by those skilled in the art thatvarious changes and modifications can be made therein without departingfrom the scope of the invention as defined in the appended claims.

What is claimed is:
 1. An apparatus for delivering radiant energy beamsonto an area of a cornea of an eye centered on a main optical axis, thecombination comprising:a source of radiant energy beam aimed along themain optical axis; a support; an array of discrete central reflectormeans, arranged about the main optical axis, for intercepting theradiant energy beam incident thereon, splitting the beam into aplurality of beam portions, and reflecting each beam portion outwardlyof the main optical axis; first means, coupled to said support and saidarray of central reflector means, for coupling said central reflectormeans to said support; an assembly of discrete peripheral reflectormeans, outwardly spaced from said central reflector means, eachperipheral reflector means for intercepting one of said reflected beamportions from an associated central reflector means and for directingsaid intercepted beam portion generally along the main optical axis andfor incidence onto an area of the cornea; and second means, coupled tosaid support and said peripheral reflector means, for coupling saidperipheral reflector means to said support, each of said peripheralreflector means including means for focusing said intercepted beamportion onto an area of the cornea separate and discrete from theincidence of remaining said intercepted beam portions reflected ontoareas of the cornea and in a linear configuration.
 2. An apparatusaccording to claim 1, whereinsaid second means comprises means forsupporting said array of central reflector means for angular movementrelative to said assembly of peripheral reflector means.
 3. An apparatusaccording to claim 1, whereinsaid first and second means comprisesmeans, coupled to said array of central reflector means and saidassembly of peripheral reflector means, for fixedly interconnecting saidarray and said assembly, and means for rotatably supporting saidinterconnected array and assembly on said support for rotation about themain optical axis, and means for rotating said interconnected array andassembly.
 4. An apparatus according to claim 1, whereinsaid centralreflector means are mirrors.
 5. An apparatus according to claim 1,whereinsaid peripheral reflector means are mirrors.
 6. An apparatusaccording to claim 1, whereinsaid central reflector means have flatreflective surfaces.
 7. An apparatus according to claim 1, whereineachof said means for focusing comprises a curved reflective surface.
 8. Anapparatus according to claim 1, whereineach of said means for focusingcomprises a substantially semi-cylindrical reflective surface.
 9. Anapparatus according to claim 1, whereineach of said means for focusingcomprises a reflective surface that is curved about an axis A and iscurved about an axis B which is perpendicular to axis A.
 10. Anapparatus according to claim 1, whereineach of said means for focusingcomprises a reflective surface that is curved about an axis A, andhaving a radius of curvature varying therealong.
 11. An apparatusaccording to claim 1, and further comprisingsaid peripheral reflectormeans are holographic elements.
 12. An apparatus according to claim 1,whereinsaid array of central reflector means includes from two to eightcentral reflector means, and said assembly of peripheral reflector meansincludes from two to eight peripheral reflector means.
 13. An apparatusaccording to claim 1, whereinsaid array of central reflector means is anoctagonal array.
 14. An apparatus according to claim 1, and furthercomprisingmeans, coupled to said support, for reflecting a part of thebeams reflected by said peripheral reflector means and determining thelength of the beams from the source and the energy distribution of thebeams.
 15. An apparatus according to claim 1, and further comprisinganeye positioning device coupled to said support for positioning thecornea relative to said central reflector means.
 16. An apparatusaccording to claim 15, and further comprisingconduit means coupled tosaid eye positioning device for delivering fluid to the cornea.
 17. Anapparatus according to claim 1, whereineach of said means for focusingis configured to focus said intercepted beam portion onto an externalarea of the cornea for ablating an external surface of the cornea. 18.An apparatus according to claim 17, whereinsaid first and second meanscomprises means, coupled to said array of central reflector means andsaid assembly of peripheral reflector means, for fixedly interconnectingsaid array and said assembly, and means for rotatably supporting saidinterconnected array and assembly on said support for rotation about themain optical axis, and means for rotating said interconnected array andassembly.
 19. An apparatus according to claim 17, whereineach of saidmeans for focusing is further configured to focus said intercepted beamportion in a rectilinear configuration on the cornea.
 20. An apparatusaccording to claim 19, whereineach of said means for focusing is furtherconfigured to focus said intercepted beam portion along a line extendingradially, outwardly from the main optical axis of the cornea.
 21. Anapparatus according to claim 17, whereineach of said means for focusingis further configured to focus said intercepted beam portion in acurvilinear configuration on the cornea.
 22. An apparatus according toclaim 21, whereineach of said means for focusing is further configuredto focus said intercepted beam portion along a line extending radially,outwardly from the main optical axis of the cornea.
 23. An apparatusaccording to claim 22, whereinsaid first and second means comprisesmeans, coupled to said array of central reflector means and saidassembly of peripheral reflector means, for fixedly interconnecting saidarray and said assembly, and means for rotatably supporting saidinterconnected array and assembly on said support for rotation about themain optical axis, and means for rotating said interconnected array andassembly.
 24. An apparatus according to claim 21, whereineach of saidmeans for focusing is further configured to focus said intercepted beamportion along a circumferentially curved line on the cornea.
 25. Anapparatus according to claim 24, whereinsaid first and second meanscomprises means, coupled to said array of central reflector means andsaid assembly of peripheral reflector means, for fixedly interconnectingsaid array and said assembly, and means for rotatably supporting saidinterconnected array and assembly on said support for rotation about themain optical axis, and means for rotating said interconnected array andassembly.
 26. An apparatus according to claim 1, whereineach of saidmeans for focusing is configured to focus said intercepted beam portiononto an intrastromal area of the cornea without ablating an externalsurface of the cornea.
 27. An apparatus according to claim 26,whereineach of said means for focusing is further configured to focussaid intercepted beam portion in a rectilinear configuration onto theintrastromal area of the cornea.
 28. An apparatus according to claim 27,whereineach of said means for focusing is further configured to focussaid intercepted beam portion along a line extending radially, outwardlyfrom the main optical axis of the cornea.
 29. An apparatus according toclaim 28, whereinsaid first and second means comprises means, coupled tosaid array of central reflector means and said assembly of peripheralreflector means, for fixedly interconnecting said array and saidassembly, and means for rotatably supporting said interconnected arrayand assembly on said support for rotation about the main optical axis,and means for rotating said interconnected array and assembly.
 30. Anapparatus according to claim 26, whereineach of said means for focusingis further configured to focus said intercepted bee portion in acurvilinear configuration onto the intrastromal area of the cornea. 31.An apparatus according to claim 30, whereineach of said means forfocusing is further configured to focus said intercepted beam portionalong a line extending radially, outwardly from the main optical axis ofthe cornea.
 32. An apparatus according to claim 31, whereinsaid firstand second means comprises means, coupled to said array of centralreflector means and said assembly of peripheral reflector means, forfixedly interconnecting said array and said assembly, and means forrotatably supporting said interconnected array and assembly on saidsupport for rotation about the main optical axis, and means for rotatingsaid interconnected array and assembly.
 33. An apparatus according toclaim 30, whereineach of said means for focusing is further configuredto focus said intercepted beam portion along a circumferentially curvedline onto the intrastromal area of the cornea.
 34. An apparatusaccording to claim 33, whereinsaid first and second means comprisesmeans, coupled to said array of central reflector means and saidassembly of peripheral reflector means, for fixedly interconnecting saidarray and said assembly, and means for rotatably supporting saidinterconnected array and assembly on said support for rotation about themain optical axis, and means for rotating said interconnected array andassembly.
 35. A method of ablating an area of a cornea via a radiantenergy beam, comprising the steps ofaligning a source of radiant energybeam and the cornea along a main axis, emitting the radiant energy beamfrom the source, splitting the beam into a plurality of beam portionsand reflecting those beam portions outwardly of the main axis,reflecting the outwardly directed beam portions generally along the mainaxis to produce a plurality of output beam portions, and directing andfocusing each of the output beam portions for incidence onto the corneain an area separate and discrete from the incidence of remaining outputbeam portions reflected onto areas of the cornea and in a linearconfiguration.
 36. A method according to claim 35, whereinthe directingand focusing step includes focusing the output beam portions ontointrastromal areas of the cornea for ablating the intrastromal areaswithout ablating an external surface of the cornea.
 37. A methodaccording to claim 36, whereinthe directing and focusing step includesfocusing the output beam portions in a rectilinear configuration ontothe intrastromal areas of the cornea.
 38. A method according to claim37, whereinthe directing and focusing step includes focusing the outputbeam portions along a line extending radially, outwardly from the mainoptical axis of the cornea.
 39. A method according to claim 38,whereinthe splitting, the two reflecting, and the directing and focusingsteps include the step of revolving the output beam portions about themain optical axis of the cornea.
 40. A method according to claim 36,whereinthe directing and focusing step includes focusing the output beamportions in a curvilinear configuration onto the intrastromal areas ofthe cornea.
 41. A method according to claim 40, whereinthe directing andfocusing step includes focusing the output beam portions along a lineextending radially, outwardly from the main optical axis of the cornea.42. A method according to claim 41, whereinthe splitting, the tworeflecting, and the directing and focusing steps include the step ofrevolving the output beam portions about the main optical axis of thecornea.
 43. A method according to claim 40, whereinthe directing andfocusing step includes focusing the output beam portions along acircumferential curved line onto the intrastromal areas of the cornea.44. A method according to claim 43, whereinthe splitting, the tworeflecting, and the directing and focusing steps include the step ofrevolving the output beam portions about the main optical axis of thecornea.
 45. A method according to claim 35, whereinthe directing andfocusing step includes focusing the output beam portions onto externalareas of the cornea for ablating the external areas of the cornea.
 46. Amethod according to claim 45, whereinthe directing and focusing stepincludes focusing the output beam portions in a rectilinearconfiguration on the cornea.
 47. A method according to claim 46,whereinthe directing and focusing step includes focusing the output beamportions along a line extending radially, outwardly from the mainoptical axis of the cornea.
 48. A method according to claim 47,whereinthe splitting, the two reflecting, and the directing and focusingsteps include the step of revolving the output beam portions about themain optical axis of the cornea.
 49. A method according to claim 45,whereinthe directing and focusing step includes focusing the output beamportions in a curvilinear configuration on the cornea.
 50. A methodaccording to claim 49, whereinthe directing and focusing step includesfocusing the output beam portions along a line extending radially,outwardly from the main optical axis of the cornea.
 51. A methodaccording to claim 50, whereinthe splitting, the two reflecting, and thedirecting and focusing steps include the step of revolving the outputbeam portions about the main optical axis of the cornea.
 52. A methodaccording to claim 49, whereinthe directing and focusing step includesfocusing the output beam portions along a circumferential curved line onthe cornea.
 53. A method according to claim 52, wherein the splitting,the two reflecting, and the directing and focusing steps include thestep of revolving the output beam portions about the main optical axisof the cornea.